1. Field of the Invention
The present invention relates to a manufacturing method of a semiconductor device.
2. Description of the Related Art
In manufacturing a semiconductor device, there is a case that an interlayer insulating film is formed on a semiconductor substrate (a metal interconnection, a P+-type silicon substrate and an N+-type silicon substrate), and a contact hole is formed to pass through the interlayer insulating film. In this case, a barrier metal layer is sometimes formed in a bottom portion and a sidewall portion of the contact hole. An interconnection plug or a contact plug is formed in the contact hole in which the barrier metal layer has been formed. In recent years, metals exemplified by tungsten (W), titanium (Ti), cobalt (Co), aluminum (Al), and copper (Cu) are mainly used as a material for the interconnection plug of the semiconductor device. In forming the interconnection plug, tungsten of these metals is predominantly used in a CVD method, whereas aluminum and copper are mainly used in a sputtering method. Especially, tungsten is frequently used for its performance and convenience of usage.
In forming a tungsten layer for the interconnection plug by the CVD method, a tungsten hexafluoride (WF6) gas is used as a gas halide, and a hydrogen (H2) gas and a silane (SiH4) gas are used as reducing gas. In this case, the tungsten layer contains a high concentration of fluorine (approximately 1.2×1020 atm/cm3), since the gas halide (WF6 gas) is used. For example, when a tungsten plug is formed on a metal interconnection layer, fluorine contained the tungsten plug reacts with the metal interconnection layer in the interface between the metal interconnection layer and the barrier metal layer to increase interface resistance.
In conjunction with the above description, a wiring method is disclosed in Japanese Laid Open Patent Application (JP-P2000-77417A). In this conventional example, a barrier metal layer is formed on a semiconductor substrate, and a metal layer is formed on the barrier metal layer by a chemical vapor deposition method by using a source gas containing a fluorine component. Then, a metal layer pattern is formed by etching the metal layer, and residual fluorine in the barrier metal layer is removed by applying a hydrogen plasma process.
Also, a method of manufacturing a tungsten layer in a semiconductor device is disclosed in Japanese Laid Open Patent Application (JP-P2000-133715A). In this conventional example, an interface metal film formed on a semiconductor substrate is processed by using a SiH4 gas with the pressure of 5.2 KPa or above, and a tungsten seed layer is formed on the processed boundary metal film by using the WF6 gas and the SiH4 gas, in which a flow ratio on the interface metal layer surface is [WF6]/[SiH4]≦1. Then, a tungsten layer is formed by using the WF6 gas on the interface metal film on which the tungsten seed layer has been formed.
Also, a method of manufacturing a semiconductor device is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 08-306781). In this conventional example, an interlayer insulating film is formed on a semiconductor substrate, and an opening is formed in a predetermined position of the interlayer insulating film. Then, a barrier layer containing titanium nitride is formed in a whole area including the opening, and a tungsten layer is formed to fill the opening by a chemical vapor deposition method. Subsequently, the tungsten layer is etched by using a gas containing fluorine as a reactive gas in a first chamber to remain the tungsten layer only in the opening, and then a wafer is transferred from the first chamber to a second chamber without breaking a vacuum. Subsequently, fluorine adhered on the substrate surface is removed in the second chamber.
Also, a method of forming a conductive plug in a contact hole with a high aspect ratio is disclosed in Japanese Laid Open Patent Application (JP-P2002-93746A). In this conventional example, the conductive plug is formed in a through-hole or a contact hole by introducing a reactive gas into a chamber. At this time, the deposition of a conductive film is promoted by introducing the reactive gas into the chamber. Also, the gas in the chamber is exhausted. Then, the introduction and the exhaustion are alternately repeated.
Also, a method of manufacturing a semiconductor device is disclosed in Japanese Laid Open Patent Application (JP-P2003-22985A). In this conventional example, a CoSi2 layer is formed in a predetermined region on a silicon substrate, and an insulating film is deposited on the whole silicon substrate. A contact hole is formed to pass through the insulating film to the CoSi2 layer, and a titanium film is deposited by a sputtering method to cover the inside of the contact hole. Subsequently, a titanium nitride film containing carbon is deposited on the titanium film by using an organic titanium material by a chemical vapor deposition method. Then, carbon is removed from the titanium nitride film at least by exposing the surface of the titanium nitride film to plasma of hydrogen or nitrogen. Subsequently, a tungsten layer is deposited on the titanium nitride film by using a tungsten hexafluoride gas and a monosilane gas by the chemical vapor deposition method. At this time, the film thickness of the titanium nitride film deposited once is set to be equal to or less than such a thickness that moisture to be absorbed into the film when being exposed to the atmosphere can be restricted. Also, the deposition of the titanium nitride film and the removal of carbon are repeated several times to form the titanium nitride film with a desired film thickness.
Also, a method of manufacturing a semiconductor device is disclosed in Japanese Laid Open Patent Application (JP-P2001-210711A). In this conventional example, a first interlayer insulating film is formed on a silicon substrate, and an opening is formed in the first insulating film. Then, a Si plug is formed in the opening by filling a Si layer in the first interlayer insulating film. Then, a silicide pad is formed on an upper end of the silicon plug in a self-alignment to have a diameter larger than that of the opening. An upper surface of the silicide pad is positioned above an upper surface of the first interlayer insulating film.